1. Cell Biology and Radiation Genetics
Dr.Sayed abbas
NMT 232
L 7

2. Mechanisms of Damage
Injury to living tissue results from the transfer of energy to atoms and molecules in the cellular structure. Ionizing radiation causes atoms and molecules to become ionized or excited. These excitations and ionizations can:
Produce Damage molecules that regulate vital cell processes (e.g. DNA, RNA, proteins).

4. Tissue Sensitivity
In general, the radiation sensitivity of a tissue is:
proportional to the rate of proliferation of its cells
inversely proportional to the degree of cell differentiation Most Sensitive:  Blood-forming organs
Reproductive organs
Skin
Bone and teeth
Muscle
Least sensitive: Nervous system
التكاثر :proliferation

5. Radiosensitivities of various tissues
ovarian follicle :جراب المبيض

6. the thin tissue forming the outer layer of a body's surface and lining the alimentary canal and other hollow structures.Epithelium :

7. Ganglion : عقدة عصبية

8. Prompt Effects
High doses delivered to the whole body of healthy adults within short periods of time can produce effects such as blood component changes, fatigue, diarrhea, nausea and death. These effects will develop within hours, days or weeks, depending on the size of the dose. The larger the dose, the sooner a given effect will occur. 
تأثيرات سريعةPrompt Effects :

9. Prompt Effects Effect Dose Blood count changes 50 rem
Vomiting (threshold)
100 rem
Mortality (threshold)
150 rem
LD50/60* (with minimal supportive care)
320 – 360 rem
LD50/60 (with supportive medical treatment)
480 – 540 rem
100% mortality (with best available treatment)
800 rem 
معدل الوفياتMortality: LD50/60 :stands for Lethal Dose for 50 to 60 Percent of Exposed Individuals Thresholdالبداية /عتبة : :

10. Delayed Effects of Radiation Exposure
These acute effects apply only when the whole body is relatively uniformly irradiated. Cataracts: induced when a dose exceeding approximately rem is delivered to the lens of the eye. Cancer: associated with high doses. include leukemia, multiple myeloma, breast cancer, lung cancer, and skin cancer. take years or more to appear.
حاد Acute :

12. Genetic Effects
Prenatal Radiation Exposure: radiation exposure can produce developmental problems, particularly in the developing brain, when an embryo/fetus is exposed prenatally effects are include low birth weight, microcephaly, mental retardation, and other neurological problems. The threshold dose for developmental effects is approximately 10 rems.
The threshold dose : beginning, start
بداية

13. Bergonie and Tribondeau Law Radiosensitivity is based on the metabolic state of the tissue being irradiated
The radiosensitivity of a tissue depends on:
1- The excess amount of less-differentiated cells in the tissue.
2- The excess amount of active mitotic cells.
3- The duration of active proliferation of the cells.
differentiate: متميزة / Stem cells, younger tissue and organs, and tissues with high metabolic ratesless-differentiated cells Are more radiosensitive

14. According to the Bergonie and Tribondeau law, the effect of radiation on undifferentiated divided cells
with high mitotic activity is much greater than the effect of radiation on undivided differentiated cells .
Undifferentiated  : cell that has not assumed the morphologic and  functional characteristics it will later acquire .
Differentiated : Is a cell in a multicellular organism that is specialized in its function
High cell proliferation rate
Results in a high radiosensitivity of the tissue

15. any of a group of basic proteins found in chromatin :Histones :

16. Thank you